WASHINGTON — The question in a case argued Monday in the Supreme Court sounded both irresistible and important: Did a California police department violate the Constitution by reading sexually explicit text messages sent by an officer on a department-issued pager?

But the tangled factual record, uncertainty about where technology is heading and occasionally muddled advocacy pointed toward a limited ruling that might provide little guidance to government employers and perhaps none to private ones.

“I just don’t know how you tell what is reasonable,” Chief Justice John G. Roberts Jr. said. “I suspect it might change with how old people are and how comfortable they are with the technology.”

The Supreme Court has said the Fourth Amendment, which forbids unreasonable government searches, figures in the analysis when public employers search their employees’ offices and files.

The chief justice appeared sympathetic to the police officer in the case, Sgt. Jeff Quon of the Ontario Police Department’s SWAT team, who had received mixed guidance from his superiors about the status of messages sent on his pager. The messages included communications to and from his wife and mistress.

The department’s written policy allowed “light personal communications” but cautioned employees that they “should have no expectation of privacy.” Under an informal policy adopted by a police lieutenant, however, those who paid for messages over a monthly maximum would not have their records inspected.

Roberts said the combination of the two policies might be enough to give Quon a reasonable expectation of privacy under the Fourth Amendment. “I think if I pay for it,” the chief justice said, “it’s mine and not the employer’s.”

Neal K. Katyal, a deputy solicitor general, disagreed, saying that a low-level employee had no power to change a general policy. “The computer help desk cannot supplant the chief’s desk,” Katyal said.